Subject: NA-NET distribution message

From: [email-masked]
Date: Sun, 13 Aug 89 08:51:40 PDT

NA Digest   Sunday, August 13, 1989   Volume 89 : Issue 31

Today's Editor: Cleve Moler

Today's Topics:

     NAG Replies to Proskurowski
     Algorithms and Parallel VLSI Workshop
     Address Change for Zlatev
     Where is George Marsaglia
     FFT's for Solving Elliptic Equations

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From: Peter Mayes <[email-masked]>
Date: Mon, 7 Aug 89  17:05 BST
Subject: NAG Replies to Proskurowski

We would like to thank Professor Proskurowski for his comments on the
NAG multigrid routine D03EEF and its documentation.

Firstly a few words on the philosophy behind the example programs to be
found in the NAG Library manual. These programs are really intended to
give a simple example of how to set up a problem, call the routine and
interpret the results. They are not designed to show the full
capabilities of any particular routine, nor are they intended to show
the behaviour of the routine on particularly "difficult" or "special"
examples. In addition, they are not intended to test the implementation
of the underlying numerical algorithm. For this we have a separate set
of "stringent" test programs. 

Turning to the particular routine D03EEF, the example chosen has a
quadratic solution, with zero truncation error for central differences.
This has the unintentional advantage that it gives a demonstration of 
the correctness of the implementation in this case. In fact, the results
given by Professor Proskurowski are in good agreement with the multigrid
theory. However, the example has the disadvantage that it gives the
wrong impression about what the user is likely to see from his/her own
problem. It would have been better to give as an example a problem for
which second-order differences gave only second-order accuracy.

We are currently in the process of finalising code and documentation for
Mark 14, and we will change the example to treat a less "special" case. 

Thank you very much

Peter Mayes, NAG

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From: Harry Nelis <[email-masked]>
Date: Wed, 9 Aug 89 14:35:45 met
Subject: Algorithms and Parallel VLSI Workshop

                          International Workshop on
                  Algorithms and Parallel VLSI Architectures
                             June 10--16, 1990
                            Les Houches, France

                      Announcement and Call for Papers

  Conference Committee
  
  Ed Deprettere                          Patrick Dewilde
  Dept. of Electrical Engineering        Dept. of Electrical Engineering
  Delft University of Technology         Delft University of Technology
  email: ed@dutentb                      email: dewilde@dutentb
  
  Thomas Kailath                         Sun-Yuan Kung
  Information Systems Laboratory         Dept. of Electrical Engineering
  Stanford University                    Princeton University
  email: [email-masked]             email: [email-masked]
  
  Henk van der Vorst                     Prabhakar Rao
  Dept. of Mathematics                   Dept. of Electrical Engineering
  Delft University of Technology         Drexel University
  email: numan@dutinfd                   email: rao@drexel

  The workshop will consist of a number of courses and workshops.
  The following topics will be covered:
   
                                Courses
       
                Schur's Algorithm and its Applications
                Array Forms of Fast Signal Processing Algorithms
                Architecture Design
                Multiscale Signal Processing
                Large Scale Modeling
                Solving Large Systems of Linear Equations
           
                              Workshops

    Computer Graphics             Modeling with Finite Elements
    Signal Estimation             Adaptive and Orthogonal Filtering
    Video Architectures           Architectures for Control and Communications
    Microcoded Architectures      Systolic Architectures
    Artificial Neural Nets        Eigenvalues and Singular Values
  
  The courses will be given by eminent lecturers in the field (names will be
  announced shortly).
  The workshops will consist of plenary talks by invited speakers and poster 
  sessions.
  We plan to have one course and two workshops per day.
  Papers are solicited for contributions to the workshops, and will have to be
  presented in poster format.
  Authors are invited to submit four copies of a 4-page summary of the paper to
  the workshop secretariat for review.
  Papers will be severely reviewed --- the number of accepted papers is limited.
  Authors of accepted papers will be asked to prepare a version for publication.
      
                           Authors' Schedule

  Submission of 4-page summary: Februari 19, 1990
  Notification of Acceptance:   March 30, 1990
  
                         Workshop Secretariat
  
  Harry Nelis
  Dept. of Electrical Engineering
  Delft University of Technology
  2628 CD Delft, The Netherlands
  email: harry@dutentb

------------------------------

From: Zahari Zlatev <[email-masked]>
Date: Wed, 9 Aug 89 11:18:20 -0500
Subject: Address Change for Zlatev

     My stay at the Center for Supercomputing Research and Development
     at the University of Illinois at Urbana-Champaign is finishing
     soon. After August 17 I shall be back in Denmark at the old
     address:

               Air Pollution Laboratory
               Danish Agency for Environmental Protection
               Risoe National Laboratory
               DK-4000 Roskilde, DENMARK

     E-mail address:  [email-masked]
                  or  [email-masked]

------------------------------

From: Jim Walker <[email-masked]>
Date: 10 Aug 89 13:21 -0600
Subject: Where is George Marsaglia

Does anyone have the email address and FAX number for George Marsaglia 
(random numbers etc.)

Jim Walker.

------------------------------

From: John D. McCalpin <[email-masked]>
Date: 11 Aug 89 12:38:35 GMT
Subject: FFT's for Solving Elliptic Equations

I would like to be able to use an FFT-based method for solving a
finite-difference version of a linear, separable elliptic equation
with Neumann boundary conditions. I routinely use this technique to
solve the same problem with periodic boundaries in one or both
directions.

The one unusual aspect of this problem is that the derivative of the
solution is not specified at a grid point, but exactly midway between
two grid points.  (This is a natural specification of a derivative for
the finite-difference part of the equation).

It seems that it should be possible to "twiddle" with the transformed
variables to introduce the appropriate phase shift, but I can't figure
out how to do it.

Solutions which are only first-order accurate in space are not
interesting. On the other hand, the value of the derivative at the
boundaries is _almost_ zero, and I may be able to get away with 
calling it zero and trying to use a cosine transform  -- if I can
figure out how to apply the appropriate phase shift.

Any pointers wil be appreciated!

John D. McCalpin - [email-masked] - [email-masked]
		   [email-masked]
Supercomputer Computations Research Institute

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